In the refining of various ore concentrates such as, for example, uranium ore concentrates, there are produced aqueous waste streams which contain low, yet significant, levels of byproduct nitrate compounds, e.g., byproduct ammonium nitrate. Although the levels of the byproduct in these streams are low, the byproduct itself usually is of sufficient commercial value to render its recovery desirable. In general, however, such recovery has not been attempted in the past due, in part, to the technical difficulties perceived to be inherent in the processing of such streams.
These perceived technical difficulties arise as the result of the further presence in the above described aqueous waste streams of calcium ions and various anionic species. Under appropriate conditions, such as elevated temperatures, the calcium ions and the various anionic species can react with each other to form insoluble process disrupting materials which can, and do, adhere to internal surfaces of process equipment. For example, aqueous waste streams recovered from the refining of uranium ore concentrates are known to contain, in addition to the byproduct ammonium nitrate therein, both calcium and sulfate ions. Any attempt to concentrate the byproduct ammonium nitrate in these streams using conventional elevated temperature evaporative processes would result in these ions reacting with one another to form scaly deposits of calcium sulfate species within the evaporative equipment employed. As these deposits accumulate over a period of time, complete fouling or blockage of the evaporative equipment frequently would occur. Therefore, the need to frequently shut down such evaporative processes for removal of these deposits from the evaporative equipment would render the use of these processes both uneconomical and highly inefficient.